Balanced rotary pump



Feb 10, 1942. w DAVIS BALANCED ROTARY PUMP Filed No v. 3,1939

NTOR

' ATTO EYE Patented Feb. 10, 1942 STATES PATENT BALANCED ROTARY PUMP Walwin L. Davis, Avon, Ohio Application November 3, 1939, Serial No. 302,737

2 Claims.

This invention relates to rotary pumps of the type having vanes which extend through the piston, and as its principal object, aims to provide an improved rotary pump of this type in which the cylinder is of non-circular contour and the vanes are of curved or arcuate shape and cooperate therewith in a manner to produce a smooth and elficient pumping operation.

Another object of my invention is to provide an improved rotary pump having a cylinder of non-circular but symmetrical contour, and a piston rotatable in the cylinder so as to divide the same into working chambers of substantially equal Volume and having curved slidable vanes whose opposite edges are continuously in engagement with the non-circular contour of the cylinder and cooperate therewith to produce a smooth and efficient pumping action in which the loads on the piston are in opposed substantially balanced relation.

Still another object of my invention is to provide an improved rotary pump, of the type mentioned, in which the non-circular contour of the cylinder isof such shape that the fluid delivery of the p"mp will be a substantially constantvelocity or non-pulsating flow.

A further object of my invention is to provide an improved rotary pump, of the type mentioned, in which the non-circular contour of the cylinder is of a shape such that the movement of the curved vanes relative to the piston will take place with a substantially constant acceleration.

Other objectsand advantages of my invention will be apparent from the following description ing sheet of drawings in which:

Fig. 1 is a transverse sectional view taken through a balanced rotary pump embodying my invention;

Fig. 2 is a similar transverse sectional view taken through another form of. my improved Fig. 3 is a perspective view showing one of the curved vanes in detached relation; and

Fig. 4 is a perspective view of one of the contact elements of the curved vanes.

My invention will now be described in greater detail, and in so doing, reference will be made to the particular embodiments illustrated in the drawing, but it should be understood that my invention is not limited to the particular pumps illustrated because it can be embodied in various other pumps and similar or analogous devices.

prises a housing ID of suitable shape having pairs of inlet and discharge passages H and I2 therein, and a piston 13 carrying a plurality of curved vanes l4 androtatable in the housing for causing a flow of fluid through said inlet and discharge passages. The piston l3 may operate directly in the housing 10, or preferably as shown in this instance, operates in a cylinder liner I5 which is mounted in the housing and has pairs of openings or ports l6 and I1 therethrough which communicate respectively with the pairs of inlet and discharge passages H and 12 of the housing. The outer surface of the liner l5 may be cylindrical in shape for convenient mounting in the housing I0 and, as will be explained hereinafter, its inner surface defining the cylinder chamber I8 is non-circular but has a cross-sectional shape which is substantially symmetrical with respect to'its major and minor axes. In other words, the internal contour of the liner I5 forming the outer wall of the cylinder chamber I8 is of a generally elliptical shape.

The piston l3 may. comprise an elongated body of substantially circular cross-section which is mounted for rotation in the housing and liner with substantially diametrically opposed sections thereof in arcuate running contact with the liner as indicated at IS. The piston thus divides the-cylinder 18 into two opposed working chambers 20 and 2| of substantially equal volume. An inlet passage or port 16 and a discharge passage or port I! communicates with i when taken in conjunction with the accompanyeach of these working chambers. The piston may be rotatably supported by means of an axial projection or shaft member 22, on one or both ends thereof, which is journaled in a suitable bearing of the housing H1 or of the end wall of the liner i5.

The body of the piston I3 is provided with a plurality of pairs of arcuately extending slots 23 corresponding in number with the number of vanes to be mounted in the piston. In this instance the piston is provided with four pairs of such arcuate slots 23 which accommodate the four curved vanes l4. These curved vanes are so constructed that when arranged in the piston in their respective pairs of slots 23, each vane will have a constant chord length, that is, will span a section of the wall of the cylinder with its opposite side edges in running engagement with such wall and will slide in the piston slots as the piston rotates. The angular distance or section of the cylinder wall spanned by each vane will depend upon the number of vanes My improved pump, as shown in Fig. 1, commounted in the piston and, in thearrangement illustrated where the piston is provided with four' of these curved vanes, each vane may span approximately a 90 section of the cylinder wall.

From the arrangement thus far described, it will be seen that as the piston 13 rotates, the opposite edges of the vanes M will be in continuous contact with the non-circular inner wall of the cylinder chamber and that the edge sections of the vanes will be projected in succession from the piston so as to sweep through the lobular working chambers and 2| thereby causing fluid to be drawn in through the inlet passages and delivered through the discharge passages. With the working chambers 20 and 2| arranged on opposite sides of the piston l3, as shown in the drawing, the pressures built up in these chambers will act on the piston substantially in opposition to each other and the loads on the piston and its bearing or bearings will be substantially balanced.

When two pairs of curved vanes are provided in the'piston l3 as shown in the present embodiment, it is desirable to arrange the vanes in intersecting relation to each other and to this end I construct the vanes M of substantially C-shape or U-shape, as shown in Fig. 3, or in other words,

with a recess 24 extending axially thereof and opening through one end of the vane. To permit assembly of the vanes inthe piston 13 in this intersecting or interfitting relation, the body of the piston may have the slots 23 open-through an end thereof as could be the case when the shaft member 22 is provided on one end only,

or it may be formed of sections which are suitably connected together after the vanes have been inserted. As will be seen from Figs. 1 and 3, the vanes each have a body formed of one piece of material and the vanes may, therefore, be referred to as of one-piece construction. The vanes may operate with the edges thereof in direct contact with the cylinder wall, or as shown in this instance, their edges may have longitudinal arcuate grooves 25 formed therein and contact elements 26 may be mounted in these grooves for sealing and bearing engagement with the inner wall of the cylinder.

I have stated above that the wall of the cylinder chamber I3 is of non-circular but symmetrical contour and that diametrically opposed sections of the piston are in running contact with the cylinder wall and also that the curved vanes Ml have their opposite edges in continuous engagement with the wall of the cylinder during rotation of the piston. The non-circular cylinder contour providing for this arrangement and operation may be obtained from various specific shapes, but, in the pump illustrated in Fig. 1, the non-circular contour is of a shape which will result in a substantially constant-velocity flow of the liquid being delivered through the discharge passages. In other words, I make the non-circular contour of the cylinder chamber iii of such shape that the piston and curved vanes will operate therein in the manner above explained and such that the stream of fluid delivered by the pump will be a substantially nonpulsating stream.

One way of obtaining this desired shape for the cylinder chamber is to construct the liner It so that the end portions of the working chambers 20 and 2! are arcs struck with the same radius from a common center lying on the axis of rotation of the piston. The contact sections it between the piston and the liner are also arcs which are struck from the same center as the Eiii arcs defining the ends of the working chambers 20 and 2! but with a shorter radius. The curved sections 28 of the cylinder wall joining these pairs of arcs are so formed or generated that they connect the arcs smoothly with each other and accommodate the curved vanes in a manner such that the opposite edges thereof remain continuously in contact with the non-circular wall of the cylinder during rotation of the piston.

In Fig. 2 I show another form of my balanced rotary pump which embodies the same principles as those explained above but in which the nonciroular contour of the cylinder chamber has a different shape, as will be presently explained. This modified form of my rotary pump includes a housing 30 having a cylinder liner 3i therein, and a piston 32 rotatable in the liner and carrying pairs of curved vanes 33 of constant chord length. The inner face of the liner 3| defines a cylinder chamber 34 which is of non-circular contour but substantially symmetrical in cross-section and of generally elliptical shape.

The body of the piston 32 may be of substantially circular shape and the piston may be mounted for rotation in the housing with diametrically opposed sections thereof in running contact with the liner, as indicated at 35, so that the piston divides the cylinder chamber into two lobular or crescent-shape working chambers 36 and 31 of substantially equal volume.

The pump illustrated in Fig. 2 being similar to that of Fig. 1 need not be described in greater detail except for the shape of the non-circular contour of the cylinder chamber 34 which is different and produces a different result in the operation of the pump. The non-circular wall of the cylinder chamber 34 is so shaped that the curved vanes 33 will have constant acceleration during their movement in the curved slots of the piston 32. To obtain this desired result the shape of the non-circular contour of the cylinder chamber 34 should be such that the curves 3B, defining the four quadrantal wall sections intercepted by the minor and major axes, are parabolic curves or are curves or arcs having a shape or curvature approaching or approximating that of parabolic curves. The adjacent ends of the curved sections 38 -may merge smoothly into each other or may be smoothly connected by generated sections or arcs 35a and 39.

It will be understood, of course, that the two inlet passages and the two discharge passages of the pumps illustrated can be suitably connected together by piping, or otherwise, so as to provide a common inlet and a common discharge. On the other hand my pump could be operated to handletwo separate streams of fluid if this were desirable.

From the foregoing description and the accompanying drawing, it'will be readily understood that I have provided an improved construction for balanced rotary pumps in which the cylinder chamber is of non-circular contour and curved one piece vanes carried by the piston have their opposite edges in continuous engagement with the non-circular wall of the cylinder during the rotation of the piston. It will be seen furthermore that in a balanced pump embodying this construction, the forces on the piston will act in opposition to each other thereby reducing the bearing loads. Moreover, it will be seen that by forming the non-circular cylinder chamber with a contour having either of the specific shapes described above, a desired new operating function can be obtained. With one of these shapes a constant-velocity or non-pulsating flow of the liquid being delivered is obtained and with the other ,shape the movement of the vanes relative to the piston takes place with a constant acceleration.

While I have illustratedand described my improved rotary pump in a more or less detailed manner, it will, be understood, of course, that I do not wish to be-limited to the specific constructions andarrangements herein disclosed, but regard, my invention asv including such changes and modifications as do notconstitute a departure from the spirit of the invention and the scope of the appended claims.

Having thus described my invention, I claim:

1.-In a rotary pump, a housing having inlet and outlet passages and a cylinder of generally elliptical contour, a substantially circular piston rotatable in the housing with substantially diametrically opposed sections thereof in contact working chambers of substantially equal volume,.

and a plurality of pairs of curved vanes slidable in the piston and having their oppoSite edges in continuous engagement with the non-circular cylinder contour during rotation of the piston, said vanes having a one-piece body of substantially C-shape and thevanes of each pair being arranged in intersecting relation to each other.

' WALWIN L. DAVIS. 

